Improvement in the manufacture of boracic acid



F. GUTZKGW.

Manufacture of Bnracic'Acid 10.131072. 1 PatentedMarch25 ,1873.

ii L4 7 ing; and consists of an upright cylinder, A,

0, branches off to remove the products of dis- NITE STATES FREDERICKGUTZKOW, OF SAN FRANCISCO, CALIFORNIA.

- IMPROVEMENT IN THE MANUFACTURE OF BORACIC ACID.

Specification forming part of Letters Patent No. 1 37,072, dated March25, 1873.

To all whom it may concern.-

Be it known that I, FREDERICK GU'rzKow, of the city and county of SanFrancisco, State of Oalifornia,have invented an Improved Process ofObtaining Boracic Acid from Borate of Lime and I do hereby declare thatthe best mode which I have discovered for performing the said process isdescribed in the following specification,together with the bestapparatus known to me for that purpose.

The nature of my invention consists of a new method of separating, bysuperheated steam, the hydrate of boracic acid from the native borate oflime.

Theapparatus which I prefer to use for that purpose is set forth in theaccompanying drawmade of common brick, about two feet in diameter andten feet high. Through the cover which closes it at the top a funnel, B,passes, and serves to introduce the mass to be distilled. Underneaththat cover a pipe or flue,

tillation. About one foot above the bottom of the cylinder A a loosegrating or false bottom, D, serves to support the contents. On a planewith the grate D an opening provided with a well-fitting door, E, isleft in the side of the cylinder to remove the exhausted mass. Below thegrate D the superheated steam enters. The pipe 0 leads into a brick ormetal-lined chamber, F, from which another pipe, G, opens into anothersimilar chamber, and thence into the atmosphere.

The superheating of the steam may be done in the well-known manner, byconducting steam through an iron apparatus heated from the outside, butIprefer to employ ordinary high-pressure steam, to make it issue in a jetfrom a nozzle, which jet sucks up and carries along the hot gas producedby the combustion of cokes in a separate fire-place, as the presence ofsuch gas does not interfere with the operation.

The temperature of the steam entering the cylinder A ought to be so highthat it will leave the cylinder at the top, after having traversed thecontents, with a temperature above the boiling-point of water, so thatno condensation of steam can take place within the cylinder.

The manner in which I operate is the following: I place a suitablequantity of powdered borate of lime into a trough, sprinkle over it somuch diluted sulphuric acid as, in the following operation, thedecomposition of the ho rate will require, and mix the stiff pulp withhalf the weight of ordinary cokes in order to. facilitate the passage ofthe steam. Then I bring this mixture through the funnel B into thecylinder A, which is still partially filled with the hot residue of aformer operation, close the funnel, and apply steam. The hydrate ofboracic acid will immediately commence to escape, with the steam,through the pipe 0, and cover the windings of 'the cham ber F in finelarge crystals. The temperature of the chamber F must be not much belowthe boiling point of water, which is effected by proper dimensions andmaterial. The steam escaping through G carries along still acomparatively small percentage of boraeic acid, and passes, therefore, asecond chamber, in which a temperature of about 190 Fahren heit allows aportion of the steam to condense. The steam which leaves this secondchamber contains practically no more boracic acid, and

may escape into the atmosphere, together with the sulphurous gas formedby the action of the cokes on any excess of sulphuric acid employed.

In the first chamber F only the dry hydrate of boracic acid will settleand form at once an article of commerce 5 in the second chamber, a weaksolution of boracic acid in water, which,

While still hot, is mixed with a little caustic lime. After cooling, theborate of lime, which is nearly insoluble in cold water, will separate.

It is added to the'native borate of lime and worked over. From time totime-say, every two hours-the steam is shut off, the door E unscrewed,the lowermost portion of the contents withdrawn, while bars, not shownin the figure, temporarily support the bulk. Then... the door issecured, a fresh portion of the borate of lim e is let in through thefunnel, steam turned on, and the operation resumed.

The mass withdrawn is entirely exhausted, and I consider it my discoverythat boracic acid can be completely expelled by steam alone in themanner described. The residue consists principally of sulphate of limeand cokes. It is thrown into a trough provided, as false bottom, with alarge-holed sieve." Water is added, which is rapidly absorbed by thegypsum. More water converts it into'a thin pulp, which the sieve onlythe cokes remain. They are,

, without any further manipulation, used over agam.

Though I prefer the apparatus described above for the distillationprocess, because it allows a continuous working, submits the mostexhausted mass to the hottest steam and the richest to the coldest, thepurpose of my invention can also be achieved by using an iron cylinderinstead of one made of brick, or by employing horizontal retorts insteadof vertical ones. The retorts, horizontal or vertical, may also beheated from the outside and ordinary steam passed through. Thus thesuperheating of the steam takes place inside the retorts.

Having thus described my invention, I do not claim the process asdescribed in the En glish patent of Bell'and Schofield in 1854.- neitherdo I claimas my invention the English patent issued to one Beatson in1855, as their processes will not answer to accomplish the objectdesigned to be effected by the use of my process; but

What I do claim, and desire to secure by Letters Patent, is-

The separation of boracic acid from borate of lime by distillation withsuperheated steam, substantially as set forth and described.

In witness whereof I have hereunto set my hand and seal.

FREDERICK GUTZKOW. [L. s.]

Witnesses:

(J. W. M. SMITH, PHILIP MAHLEB.

